Seasonal and spatial variation of solvent extractable organic compounds in fine suspended particulate matter in Hong Kong

The results of a 12-month study of more than 100 solvent extractable organic compounds (SEOC) in particulate matter (PM) less than or equal to 2.5 microm (PM2.5) collected at three air monitoring stations located at roadside, urban, and rural sites in Hong Kong are reported. The total yield of SEOC that accounts for approximately 8-18% of organic carbon (OC) determined by a thermal optical transmittance method was 125-2060 ng/m3, which included 14.6-128 ng/m3 resolved aliphatic hydrocarbons, 39.4-1380 ng/m3 unresolved complex mixtures, 0.6-17.2 ng/m3 polycyclic aromatic hydrocarbons, 41.6-520 ng/m3 fatty acids, and < 0.1-12.1 ng/m3 alkanols. Distinct seasonal variations (summer/winter differences) were observed with higher concentrations of the total and each class of SEOC in the winter and lower concentrations in the summer. Spatial variations are also obvious, with the roadside samples having the highest concentrations of SEOC and the rural samples having the lowest concentrations in all seasons. Characteristic ratios of petroleum hydrocarbons, such as carbon preference index, unresolved to resolved components, and carbon number with maximum concentration, suggest that PM2.5 carbon in Hong Kong originates from both biogenic and anthropogenic sources. The proportion of SEOC in PM2.5 from anthropogenic sources is estimated.

Clinical profile and genetic basis of Brugada syndrome in the Chinese population

OBJECTIVE

To study the clinical profile and genetic basis of Brugada syndrome in Chinese patients.

DESIGN

Prospective observational study.

SETTING

Seven regional public hospitals, Hong Kong.

MAIN OUTCOME MEASURES

The clinical and follow-up data of 50 patients (47 men, 3 women; mean age, 53 years) were collected, and genetic data of 36 probands and eight family members of three genotyped probands were analysed.

RESULTS

Eight patients survived sudden cardiac death (group A), 12 had syncope of unknown origin but no sudden death (group B), and 30 were asymptomatic before recognition of Brugada syndrome (group C). Programmed electrical stimulation induced sustained ventricular arrhythmias in 88% (7/8), 82% (9/11), and 27% (3/11) of patients in group A, group B, and group C, respectively. New arrhythmic events occurred in 50% (4/8) of patients in group A and 17% (2/12) of patients in group B after a mean follow-up period of 30 (standard deviation, 13) months and 25 (7) months, respectively. All group C patients remained asymptomatic during a mean follow-up period of 25 (standard deviation, 11) months. Five of 36 probands and three of eight family members who underwent genetic testing were found to have a mutation in their SCN5A gene.

CONCLUSIONS

Chinese patients with Brugada syndrome who are symptomatic have a high likelihood of arrhythmia recurrence, whereas asymptomatic patients enjoy a good short-term prognosis. The prevalence of SCN5A mutation among probands is 14%. Thus, Chinese patients with Brugada syndrome share with their western counterparts similar clinical and genetic heterogeneity.

Clinical profile of arrhythmogenic right ventricular cardiomyopathy in Chinese patients

OBJECTIVE

To study the clinical profile of Chinese patients with arrhythmogenic right ventricular cardiomyopathy (ARVC).

PATIENTS

Chinese patients who fulfilled the diagnostic criteria of ARVC proposed by the Task Force of the European Society of Cardiology and of the scientific council on cardiomyopathy of the International Society and Federation of Cardiology were recruited for analysis.

METHODS

Clinical data of patients with ARVC including age, sex, family history, presenting symptoms, electrocardiograph (ECG), echocardiography, cardiac catheterization, magnetic resonance imaging (MRI), electrophysiology study (EPS) and therapeutic intervention were analyzed.

RESULTS

Eleven patients (seven males) were diagnosed with ARVC. Mean age at clinical presentation was 42.6+/-14.8 years. Two patients (18.1%) had positive family history of ARVC or premature sudden cardiac death. The commonest presenting symptoms were palpitation (73%) and dizziness (46%). Spontaneous ventricular tachycardia (VT) was the presenting arrhythmia in 54% and 1 (9%) with ventricular fibrillation and cardiac arrest. Seven patients (64%) had the ECG abnormality as defined by the Task Force. Echocardiography showed right ventricular (RV) dilatation in five patients (46%) and all patients had normal left ventricular function. Nine patients (90%) had RV wall thinning or fibrofatty replacement on MRI examination. Inducible monomorphic VT was detected in four out of nine patients at EPS. All eight patients had normal coronary arteries and left ventriculogram but RV dilatation and global hypokinesia was seen in three patients. Implantable cardioverter defibrillators were implanted in five patients and two of them had shocks delivered during the follow-up period.

CONCLUSION

In this study, familial incidence of premature sudden death in patients with ARVC appears to be low and left ventricular involvement in affected individuals is uncommon. MRI is still the best investigation for ARVC.